Electrophysiology of retinal ganglion cells in the mouse: a study of a normally pigmented mouse and a congenic hypopigmentation mutant, pearl

Abstract

1. The organization of the receptive fields of retinal ganglion cells in te normal mouse was studied qualitatively in recordings from 43 single axons in the optic nerve and optic tract, and the light sensitivity was studied quantitatively in 26 of these cells by measuring incremental sensitivity. 2. The receptive fields of normal animals were elliptical, had concentric center and peripheral subdivisions, and had an antagonistic center/surround organization; the receptive-field centers ranged from 1.95 to 83 degrees in diameter, with a median of 7 degrees. 3. The incremental sensitivity to white light was measured using a criterion response of 10 extra spikes; the most sensitive dark-adapted cell required a stimulus luminance of 3.5 x 10(-3) cd/m2 to generate a criterion response. 4. The action spectrum measured at seven different wavelengths (433-619 nm) from ganglion cells in the normally pigmented mouse resembled the CIE (International Commission on Illumination, CIE 1957 (11)) relative scotopic luminous efficiency function (41) and is consistent with a curve having a peak around 500 nm. 5. On light adaptation with blue light (less than 460 nm), the sensitivity to longer wavelength stimuli increased by 0.2-0.5 log units relative to the sensitivity to the shorter wavelengths; these results are compatible with the presence of a photoreceptor sensitive to long wavelengths in the normally pigmented mouse (C57BL/6J+/+). 6. The organization of the receptive fields of 48 retinal ganglion cells from the hypopigmentation mutant pearl (C57BL/6J-pe) was also studied qualitatively; the receptive field organization was similar to that of the normally pigmented mouse. 7. In 25 cells from dark-adapted pearl mice, the incremental sensitivity to white light was, on the average, 1.6 log units less than that for normal mice. 8. The dark-adapted action spectrum of pearl mice was similar to that of normally pigmented mice. However, a shift in sensitivity to longer wavelengths did not occur on selective light adaptation with the most luminous blue light (less than 460 nm) background that we could produce. 9. We conclude that pearl is one of the mammalian genes that codes for functions that affect dark-adapted retinal sensitivity. The results of this study and past studies suggest that the pearl gene's action on light sensitivity is predominantly within the retina and before (distal to) the ganglion cells.